Saikali et al. describe differential compartmentalization of GATA-3 in Th cell and ILC subsets. Changing it modifies functional characteristics of the cells. Importin-β mediates GATA-3’s nuclear import. The short half-life of nuclear GATA-3 necessitates continuous GATA-3 import to maintain Th2 cell function. GATA-3’s nuclear import is a critical rheostat of lymphocytes.